Differentiated eukaryotic cells are capable of selectively expressing specific genes while others remain silent. In the nervous system the development and maintenance of differentiated cell types is the result of characteristic temporal and spatial patterns of expression of genes encoding neuronal phenotypic traits. The long-term goal of this research is to elucidate the molecular mechanisms which control the cell-specific and developmental regulation of neurotransmitter genes. The neuropeptide vasoactive intestinal peptide (VIP) will be studied as a model neurotransmitter. VIP is a 28 amino acid peptide that is present in neurons of the central, peripheral and enteric nervous systems, sparsely in cells of the adrenal medulla and ectopically in some tumors of neural crest origin. Like some other neurotransmitter genes, transcription of the VIP gene may also be controlled trans- synaptically. Three specific aims are proposed to achieve the goal of this study. First, sequences in the VIP gene which are required for cell-specific expression and the protein factors with which they interact will be identified. For these studies, the putative regulatory regions of the VIP gene will be dissected by deletional and mutational analysis, fused to an easily assayable transcriptional reporter gene and tested for biological activity in VIP-containing cell lies and in transgenic mice. Second, the hypothesis will be tested that the characteristic temporal and spatial expression of the VIP gene in the rodent nervous system can be attributed to the synthesis of VIP cell- specific protei factors. Third, it will be determined if cooperative interactions between cell-specific factors ad core promotor factors, are important in the cell-specific transcriptional control of the VIP gene. Elucidation of the molecular mechanisms of cell-specific expression of the VIP gene will increase our understanding of how multiple cis-acting genetic elements art combinatorily to control gene transcription in neural cells. These studies will also provide a framework for understanding the molecular events that control the appearance and maintenance of neuronal phenotypic traits and the ectopic production of neurotransmitters in some tumors of neural crest origin.